IPv6 maintenance Working Group (6man) F. Gont
Internet-Draft SI6 Networks / UTN-FRH
Updates: 2464, 2467, 2470, 2491, 2492, A. Cooper
2497, 2590, 3146, 3315, 3572, Cisco
4291, 4338, 4391, 5072, 5121 D. Thaler
(if approved) Microsoft
Intended status: Standards Track W. Liu
Expires: January 9, 2017 Huawei Technologies
July 8, 2016
Recommendation on Stable IPv6 Interface Identifiersdraft-ietf-6man-default-iids-13
Abstract
This document changes the recommended default IID generation scheme
for cases where SLAAC is used to generate a stable IPv6 address. It
recommends using the mechanism specified in RFC7217 in such cases,
and recommends against embedding stable link-layer addresses in IPv6
Interface Identifiers. It formally updates RFC2464, RFC2467,
RFC2470, RFC2491, RFC2492, RFC2497, RFC2590, RFC3146, RFC3572,
RFC4291, RFC4338, RFC4391, RFC5072, and RFC5121, by removing the text
in these RFCs that required the IPv6 Interface Identifiers to be
derived from the underlying stable link-layer address, and replacing
this text with recommendations consistent with those in this
document. Additionally, this document updates RFC3315 by specifying
additional requirements on the generation of Interface Identifiers
used in Dynamic Host Configuration Protocol version 6 (DHCPv6). It
also provides advice to system administrators who employ manual
configuration. This document does not change any existing
recommendations concerning the use of temporary addresses as
specified in RFC 4941.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Gont, et al. Expires January 9, 2017 [Page 1]

Internet-Draft Default Interface-IDs July 2016
The security and privacy implications of embedding a stable link-
layer address in an IPv6 IID have been known for some time now, and
are discussed in great detail in [RFC7721]. They include:
o Network activity correlation
o Location tracking
o Address scanning
o Device-specific vulnerability exploitation
More generally, the reuse of identifiers that have their own
semantics or properties across different contexts or scopes can be
detrimental for security and privacy
[I-D.gont-predictable-numeric-ids]. In the case of traditional
stable IPv6 IIDs, some of the security and privacy implications are
dependent on the properties of the underlying link-layer addresses
(e.g., whether the link-layer address is ephemeral or randomly
generated), while other implications (e.g., reduction of the entropy
of the IID) depend on the algorithm for generating the IID itself.
In standardized recommendations for stable IPv6 IID generation meant
to achieve particular security and privacy properties, it is
therefore necessary to recommend against embedding stable link-layer
addresses in IPv6 IIDs.
Furthermore, some popular IPv6 implementations have already deviated
from the traditional stable IID generation scheme to mitigate the
aforementioned security and privacy implications [Microsoft].
As a result of the aforementioned issues, this document changes the
recommended default IID generation scheme for generating stable IPv6
addresses with SLAAC to that specified in [RFC7217], and recommends
against embedding stable link-layer addresses in IPv6 Interface
Identifiers, such that the aforementioned issues are mitigated. That
is, this document simply replaces the default algorithm that is
recommended to be employed when generating stable IPv6 IIDs.
NOTE: [RFC4291] defines the "Modified EUI-64 format" for IIDs.
Appendix A of [RFC4291] then describes how to transform an IEEE
EUI-64 identifier, or an IEEE 802 48-bit MAC address from which an
EUI-64 identifier is derived, into an IID in the Modified EUI-64
format.
In a variety of scenarios, addresses that remain stable for the
lifetime of a host's connection to a single subnet, are viewed as
desirable. For example, stable addresses may be viewed as beneficial
for network management, event logging, enforcement of access control,
Gont, et al. Expires January 9, 2017 [Page 3]

Internet-Draft Default Interface-IDs July 2016
provision of quality of service, or for server or routing interfaces.
Similarly, stable addresses (as opposed to temporary addresses
[RFC4941]) allow for long-lived TCP connections, and are also usually
desirable when performing server-like functions (i.e., receiving
incoming connections).
The recommendations in this document apply only in cases where
implementations otherwise would have configured a stable IPv6 IID
containing a link layer address. For example, this document does not
change any existing recommendations concerning the use of temporary
addresses as specified in [RFC4941], nor do the recommendations apply
to cases where SLAAC is employed to generate non-stable IPv6
addresses (e.g. by embedding a link-layer address that is
periodically randomized), nor does it introduce any new requirements
regarding when stable addresses are to be configured. Thus, the
recommendations in this document simply improve the security and
privacy properties of stable addresses.
Finally this document updates [RFC3315] by specifying additional
requirements on the generation of Interface Identifiers used in
Dynamic Host Configuration Protocol version 6 (DHCPv6), and also
provides advice to system administrators who employ manual
configuration.
2. Terminology
Stable address:
An address that does not vary over time within the same network
(as defined in [RFC7721]).
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Generation of IPv6 Interface Identifiers with SLAAC
Nodes SHOULD implement and employ [RFC7217] as the default scheme for
generating stable IPv6 addresses with SLAAC. A link layer MAY also
define a mechanism for stable IPv6 address generation that is more
efficient and does not address the security and privacy
considerations discussed in Section 1. The choice of whether to
enable the security- and privacy-preserving mechanism or not SHOULD
be configurable in such a case.
By default, nodes SHOULD NOT employ IPv6 address generation schemes
that embed a stable link-layer address in the IID. In particular,
this document RECOMMENDS that nodes do not generate stable IIDs with
the schemes specified in [RFC2464], [RFC2467], [RFC2470], [RFC2491],
Gont, et al. Expires January 9, 2017 [Page 4]

Internet-Draft Default Interface-IDs July 2016
[RFC2492], [RFC2497], [RFC2590], [RFC3146], [RFC3572], [RFC4338],
[RFC4391], [RFC5121], and [RFC5072]. The specific updates to these
documents to effectuate this recommendation are included in
Section 6.
4. Generation of IPv6 Interface Identifiers with DHCPv6
By default, DHCPv6 server implementations SHOULD NOT generate
predictable IPv6 addresses (such as IPv6 addresses where the IIDs are
consecutive small numbers).
[I-D.gont-dhcpv6-stable-privacy-addresses] specifies one possible
algorithm that could be employed to comply with this requirement.
Another possible algorithm would be to select a pseudo-random value
chosen from a discrete uniform distribution, while avoiding the
reserved IPv6 Interface Identifiers [RFC5453] [IANA-RESERVED-IID].
5. Generation of IPv6 Interface Identifiers with Manual Configuration
Network administrators should be aware of the security implications
of predictable Interface Identifiers [RFC7721], and avoid the use of
predictable addresses when the aforementioned issues are of concern.
6. Update to existing RFCs
The following subsections clarify how each of the RFCs affected by
this document are updated.
Note to the RFC Editor:
In the following subsections, the legend "[RFCXXXX]" should be
replaced with the RFC number assigned to this document, and this
note to the RFC Editor should be removed before publication of
this document as an RFC.
6.1. Update to RFC2464
The entire text of Section 4 of [RFC2464] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
The Interface Identifier [AARCH] for an Ethernet interface SHOULD
be generated as specified in [RFC7217]. Embedding a stable
link-layer address in the IID is NOT RECOMMENDED [RFCXXXX].
---------------- cut here -------------- cut here ----------------
The following text from Section 6 of [RFC2464]:
Gont, et al. Expires January 9, 2017 [Page 5]

Internet-Draft Default Interface-IDs July 2016
---------------- cut here -------------- cut here ----------------
5.1 Interface Tokens
The Interface Token (or Interface Identifier [AARCH]) for each IPv6
interface SHOULD be generated as specified in [RFC7217]. Embedding
a stable link-layer address in the IID is NOT RECOMMENDED [RFCXXXX].
All implementations MUST support manual configuration of interface
tokens to allow operators to manually change a interface token on
a per-LL basis. Operators may choose to manually set interface
tokens for reasons other than eliminating duplicate addresses.
All interface tokens MUST be 64 bits in length.
---------------- cut here -------------- cut here ----------------
6.5. Update to RFC2492
The entire text of Section 5 (and all the corresponding subsections)
of of [RFC2492] is replaced with the following text:
---------------- cut here -------------- cut here ----------------
5.1 Interface Tokens
The Interface Token (or Interface Identifier [AARCH]) for each IPv6
interface SHOULD be generated as specified in [RFC7217]. Embedding
a stable link-layer address in the IID is NOT RECOMMENDED [RFCXXXX].
All implementations MUST support manual configuration of interface
tokens to allow operators to manually change a interface token on
a per-LL basis. Operators may choose to manually set interface
tokens for reasons other than eliminating duplicate addresses.
All interface tokens MUST be 64 bits in length.
---------------- cut here -------------- cut here ----------------
6.6. Update to RFC2497
The entire text of Section 4 of [RFC2497] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
The Interface Identifier [AARCH] for an ARCnet interface SHOULD be
generated as specified in [RFC7217]. Embedding a stable link-layer
address in the IID is NOT RECOMMENDED [RFCXXXX].
---------------- cut here -------------- cut here ----------------
Gont, et al. Expires January 9, 2017 [Page 8]

Internet-Draft Default Interface-IDs July 2016
The entire text of Section 8 of [RFC2497] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
Interface Identifiers generated as specified in [RFCXXXX] mitigate
the security and privacy implications discussed in Section 1 of
such document.
---------------- cut here -------------- cut here ----------------
6.7. Update to RFC2590
The entire Section 4 and Section 4.1 of [RFC2590] is replaced with
the following text:
---------------- cut here -------------- cut here ----------------
4. Stateless Autoconfiguration
An interface identifier [AARCH] for an IPv6 Frame Relay interface
MUST be unique on a Frame Relay link [AARCH], and MUST be unique on
each of the virtual links represented by the VCs terminated on the
interface.
The interface identifier for the Frame Relay interface SHOULD be
generated as specified in [RFC7217]. Embedding a stable link-layer
address in the IID is NOT RECOMMENDED [RFCXXXX].
We note that each virtual circuit in a Frame Relay network is uniquely
identified on a Frame Relay interface by a DLCI. Furthermore, a DLCI
can be seen as an identification of the end point of a virtual circuit
on a Frame Relay interface. Since each Frame Relay VC is configured or
established separately, and acts like an independent virtual-link
from other VCs in the network, or on the interface, link, wire or
fiber, it seems beneficial to view each VC's termination point on the
Frame Relay interface as a "pseudo-interface" or "logical-interface"
overlaid on the Frame Relay interface. Furthermore, it seems
beneficial to be able to generate and associate an IPv6
autoconfigured address (including an IPv6 link local address) to each
"pseudo-interface", i.e. end-point of a VC, i.e. to each DLCI on a
Frame Relay interface.
---------------- cut here -------------- cut here ----------------
The entire Section 9 of [RFC2590] is replaced as follows:
Gont, et al. Expires January 9, 2017 [Page 9]

Internet-Draft Default Interface-IDs July 2016
---------------- cut here -------------- cut here ----------------
9. Security Considerations
Security protection against forgery or accident at the level of
the mechanisms described here is provided by the IPv6 security
mechanisms [IPSEC], [IPSEC-Auth], [IPSEC-ESP] applied to Neighbor
Discovery [IPv6-ND] or Inverse Neighbor Discovery [IND] messages.
To avoid an IPsec Authentication verification failure, the Frame
Relay specific preprocessing of a Neighbor Discovery Solicitation
message that contains a DLCI format Source link-layer address option,
MUST be done by the receiver node after it completed IP Security
processing.
---------------- cut here -------------- cut here ----------------
6.8. Update to RFC3146
The entire Section 6 of [RFC3146] is replaced with the following
text:
---------------- cut here -------------- cut here ----------------
6. STATELESS AUTOCONFIGURATION
The Interface Identifier [AARCH] for an IEEE1394 interface SHOULD
be generated as specified in [RFC7217]. Embedding a stable
link-layer address in the IID is NOT RECOMMENDED [RFCXXXX].
An IPv6 address prefix used for stateless autoconfiguration [ACONF]
of an IEEE1394 interface MUST have a length of 64 bits.
---------------- cut here -------------- cut here ----------------
6.9. Update to RFC3315
The following text in Section 11 of of [RFC3315]:
---------------- cut here -------------- cut here ----------------
Any address assigned by a server that is based on an EUI-64
identifier MUST include an interface identifier with the "u"
(universal/local) and "g" (individual/group) bits of the interface
identifier set appropriately, as indicated in section 2.5.1 of RFC2373 [5].
---------------- cut here -------------- cut here ----------------
is formally replaced with:
Gont, et al. Expires January 9, 2017 [Page 10]

Internet-Draft Default Interface-IDs July 20166.11. Update to RFC4291
The entire text of Section 2.5.1 of [RFC4291] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
2.5.1. Interface Identifiers
Interface identifiers in IPv6 unicast addresses are used to identify
interfaces on a link. They are required to be unique within a subnet
prefix. It is recommended that the same interface identifier not be
assigned to different nodes on a link. They may also be unique over
a broader scope. The same interface identifier may be used on
multiple interfaces on a single node, as long as they are attached to
different subnets.
For all unicast addresses, except those that start with the binary
value 000, Interface IDs are required to be 64 bits long, and SHOULD
be generated as specified in [RFC7217]. Embedding a stable link-layer
address in the IID is NOT RECOMMENDED [RFCXXXX].
The details of forming interface identifiers are defined in the
appropriate "IPv6 over <link>" specification, such as "IPv6 over
Ethernet" [ETHER], and "IPv6 over FDDI" [FDDI].
---------------- cut here -------------- cut here ----------------
6.12. Update to RFC4338
The entire text of Section 5 (and of all the corresponding
subsections) of [RFC4338] is replaced with the following text:
---------------- cut here -------------- cut here ----------------
5. IPv6 Stateless Address Autoconfiguration
The IPv6 Interface ID [AARCH] for an Nx_Port SHOULD be generated
as specified in [RFC7217]. Embedding a stable link-layer address
in the IID is NOT RECOMMENDED [RFCXXXX].
IPv6 stateless address autoconfiguration MUST be performed as
specified in [ACONF]. An IPv6 Address Prefix used for stateless
address autoconfiguration of an Nx_Port MUST have a length of 64
bits.
---------------- cut here -------------- cut here ----------------
Gont, et al. Expires January 9, 2017 [Page 12]

Internet-Draft Default Interface-IDs July 20166.13. Update to RFC4391
The entire text of Section 8 of [RFC4391] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
8. IPv6 Stateless Autoconfiguration
The IPv6 Interface ID [AARCH] SHOULD be generated as specified in
[RFC7217]. Embedding a stable link-layer address in the IID is NOT
RECOMMENDED [RFCXXXX].
---------------- cut here -------------- cut here ----------------
6.14. Update to RFC5072
The entire text of Section 4.1 of [RFC5072] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
4.1. Interface Identifier
Description
This Configuration Option provides a way to negotiate a unique, 64-
bit interface identifier to be used for the address autoconfiguration
[3] at the local end of the link (see Section 5). A Configure-
Request MUST contain exactly one instance of the interface-identifier
option [1]. The interface identifier MUST be unique within the PPP
link; i.e., upon completion of the negotiation, different interface-
identifier values are to be selected for the ends of the PPP link.
Before this Configuration Option is requested, an implementation
chooses its tentative interface identifier. The non-zero value of
the tentative interface identifier SHOULD be chosen such that the
value is unique to the link and, preferably, consistently
reproducible across initializations of the IPV6CP finite state
machine (administrative Close and reOpen, reboots, etc.). The
rationale for preferring a consistently reproducible unique interface
identifier to a completely random interface identifier is to provide
stability to global scope addresses (see Appendix A) that can be
formed from the interface identifier. Additionally, the tentative
interface identifier SHOULD be generated as specified in [RFC7217].
Embedding a stable link-layer address in the IID is NOT
RECOMMENDED [RFCXXXX].
If neither a unique number nor a random number can be generated, it
is recommended that a zero value be used for the interface identifier
transmitted in the Configure-Request. In this case, the PPP peer may
Gont, et al. Expires January 9, 2017 [Page 13]

Internet-Draft Default Interface-IDs July 2016
provide a valid non-zero interface identifier in its response as
described below. Note that if at least one of the PPP peers is able
to generate separate non-zero numbers for itself and its peer, the
identifier negotiation will succeed.
When a Configure-Request is received with the Interface-Identifier
Configuration Option and the receiving peer implements this option,
the received interface identifier is compared with the interface
identifier of the last Configure-Request sent to the peer. Depending
on the result of the comparison, an implementation MUST respond in
one of the following ways:
If the two interface identifiers are different but the received
interface identifier is zero, a Configure-Nak is sent with a non-zero
interface-identifier value suggested for use by the remote peer.
Such a suggested interface identifier MUST be different from the
interface identifier of the last Configure-Request sent to the peer.
It is recommended that the value suggested be consistently
reproducible across initializations of the IPV6CP finite state
machine (administrative Close and reOpen, reboots, etc).
Additionally, the value suggested SHOULD be generated as specified
in [RFC7217]. Embedding a stable link-layer address in the IID is
NOT RECOMMENDED [RFCXXXX].
If the two interface identifiers are different and the received
interface identifier is not zero, the interface identifier MUST be
acknowledged, i.e., a Configure-Ack is sent with the requested
interface identifier, meaning that the responding peer agrees with
the interface identifier requested.
If the two interface identifiers are equal and are not zero,
Configure-Nak MUST be sent specifying a different non-zero
interface-identifier value suggested for use by the remote peer. It
is recommended that the value suggested be consistently reproducible
across initializations of the IPV6CP finite state machine
(administrative Close and reOpen, reboots, etc). Additionally, the
value suggested SHOULD be generated as specified in [RFC7217].
Embedding a stable link-layer address in the IID is NOT RECOMMENDED
[RFCXXXX].
If the two interface identifiers are equal to zero, the interface
identifier's negotiation MUST be terminated by transmitting the
Configure-Reject with the interface-identifier value set to zero. In
this case, a unique interface identifier cannot be negotiated.
If a Configure-Request is received with the Interface-Identifier
Configuration Option and the receiving peer does not implement this
option, Configure-Reject is sent.
Gont, et al. Expires January 9, 2017 [Page 14]

Internet-Draft Default Interface-IDs July 2016
A new Configure-Request SHOULD NOT be sent to the peer until normal
processing would cause it to be sent (that is, until a Configure-Nak
is received or the Restart timer runs out [1]).
A new Configure-Request MUST NOT contain the interface-identifier
option if a valid Interface-Identifier Configure-Reject is received.
Reception of a Configure-Nak with a suggested interface identifier
different from that of the last Configure-Nak sent to the peer
indicates a unique interface identifier. In this case, a new
Configure-Request MUST be sent with the identifier value suggested in
the last Configure-Nak from the peer. But if the received interface
identifier is equal to the one sent in the last Configure-Nak, a new
interface identifier MUST be chosen. In this case, a new Configure-
Request SHOULD be sent with the new tentative interface identifier.
This sequence (transmit Configure-Request, receive Configure-Request,
transmit Configure-Nak, receive Configure-Nak) might occur a few
times, but it is extremely unlikely to occur repeatedly. More
likely, the interface identifiers chosen at either end will quickly
diverge, terminating the sequence.
If negotiation of the interface identifier is required, and the peer
did not provide the option in its Configure-Request, the option
SHOULD be appended to a Configure-Nak. The tentative value of the
interface identifier given must be acceptable as the remote interface
identifier; i.e., it should be different from the identifier value
selected for the local end of the PPP link. The next Configure-
Request from the peer may include this option. If the next
Configure-Request does not include this option, the peer MUST NOT
send another Configure-Nak with this option included. It should
assume that the peer's implementation does not support this option.
By default, an implementation SHOULD attempt to negotiate the
interface identifier for its end of the PPP connection.
A summary of the Interface-Identifier Configuration Option format is
shown below. The fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Interface-Identifier (MS Bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Interface-Identifier (cont)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Interface-Identifier (LS Bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Gont, et al. Expires January 9, 2017 [Page 15]

Internet-Draft Default Interface-IDs July 2016
Type
1
Length
10
Interface-Identifier
The 64-bit interface identifier, which is very likely to be
unique on the link, or zero if a good source of uniqueness
cannot be found.
Default
If no valid interface identifier can be successfully
negotiated, no default interface-identifier value should be
assumed. The procedures for recovering from such a case will
depend on the algorithm employed to generate the interface
identifier. One approach is to manually configure the
interface identifier of the interface.
---------------- cut here -------------- cut here ----------------
Additionally, the following text of Section 5 of [RFC5072]:
---------------- cut here -------------- cut here ----------------
5. Stateless Autoconfiguration and Link-Local Addresses
The interface identifier of IPv6 unicast addresses [5] of a PPP
interface SHOULD be negotiated in the IPV6CP phase of the PPP
connection setup (see Section 4.1). If no valid interface identifier
has been successfully negotiated, procedures for recovering from such
a case are unspecified. One approach is to manually configure the
interface identifier of the interface.
The negotiated interface identifier is used by the local end of the
PPP link to autoconfigure an IPv6 link-local unicast address for the
PPP interface. However, it SHOULD NOT be assumed that the same
interface identifier is used in configuring global unicast addresses
for the PPP interface using IPv6 stateless address autoconfiguration
[3]. The PPP peer MAY generate one or more interface identifiers,
for instance, using a method described in [8], to autoconfigure one
or more global unicast addresses.
is formally replaced with the following text:
Gont, et al. Expires January 9, 2017 [Page 16]

Internet-Draft Default Interface-IDs July 2016
---------------- cut here -------------- cut here ----------------
5. Stateless Autoconfiguration and Link-Local Addresses
The interface identifier of IPv6 unicast addresses [5] of a PPP
interface SHOULD be negotiated in the IPV6CP phase of the PPP
connection setup (see Section 4.1). If no valid interface identifier
has been successfully negotiated, procedures for recovering from such
a case will depend on the algorithm employed to generate the interface
identifier. One approach is to manually configure the interface
identifier of the interface.
The negotiated interface identifier is used by the local end of the
PPP link to autoconfigure an IPv6 link-local unicast address for the
PPP interface. However, it SHOULD NOT be assumed that the same
interface identifier is used in configuring global unicast addresses
for the PPP interface using IPv6 stateless address autoconfiguration
[3].
---------------- cut here -------------- cut here ----------------
6.15. Update to RFC5121
The entire text of Section 9.1 of [RFC5121] is replaced with the
following text:
---------------- cut here -------------- cut here ----------------
9.1. Interface Identifier
The MS SHOULD generate interface identifiers as specified in
[RFC7217]. Embedding a stable link-layer address in the IID is
NOT RECOMMENDED [RFCXXXX].
---------------- cut here -------------- cut here ----------------
Additionally, Section 9.2 is replaced as follows:
Gont, et al. Expires January 9, 2017 [Page 17]

Internet-Draft Default Interface-IDs July 2016
---------------- cut here -------------- cut here ----------------
9.2. Duplicate Address Detection
DAD SHOULD be performed as per "Neighbor Discovery for IP Version 6
(IPv6)", [RFC4861] and "IPv6 Stateless Address Autoconfiguration"
[RFC4862]. The IPv6 link over 802.16 is specified in this document
as a point-to-point link. Based on this criteria, it may be
redundant to perform DAD on a global unicast address that is
configured as part of the IPv6 Stateless Address Autoconfiguration
Protocol [RFC4862] as long as the following two conditions are met:
1. The prefixes advertised through the router advertisement messages
by the access router terminating the 802.16 IPv6 link are unique
to that link.
2. The access router terminating the 802.16 IPv6 link does not
autoconfigure any IPv6 global unicast addresses from the prefix
that it advertises.
---------------- cut here -------------- cut here ----------------
7. Future Work
At the time of this writing, the mechanisms specified in the
following documents might require updates to be fully compatible with
the recommendations in this document:
o "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based
Networks" [RFC6282]
o "Transmission of IPv6 Packets over IEEE 802.15.4 Networks"
[RFC4944]
o "Neighbor Discovery Optimization for IPv6 over Low-Power Wireless
Personal Area Networks (6LoWPANs)"[RFC6775]
o "Transmission of IPv6 Packets over ITU-T G.9959 Networks"[RFC7428]
Future revisions or updates of these documents should take the issues
of privacy and security mentioned in Section 1 and explain any design
and engineering considerations that lead to the use of stable IIDs
based on a node's link-layer address.
8. IANA Considerations
There are no IANA registries within this document. The RFC-Editor
can remove this section before publication of this document as an
RFC.
Gont, et al. Expires January 9, 2017 [Page 18]